After a long discussion we decided to NOT implement this. Explanation: 

Grub developers do not support grub1 anymore and creating a grub1 Debian 
package that can be installed side by side with grub2 isn't trivial. Instead 
you should use a live system (e.g. see http://grub.enbug.org/
Grub2LiveCdInstallGuide) and chroot into your existing system. If you need to 
install or want to use grub1/grub2 from Grml either use grub1, grub2 or the All-
In-One-Image bootoption from Grml live system in the boot menu and install/
configure/boot accordingly from there.

Closing this issue therefore.